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The average Social Security payment to a retired worker currently sits around $1,234 per month -- or about $14,808 per year. For comparison, a full-time minimum wage job would currently pay $7.25 per hour -- or around $14,500 per year. Or in other words, the average Social Security check would get you right around a minimum-wage lifestyle.

Unfortunately, that's the good news about Social Security. The bad news is that even that meager payout is on track to be slashed. According to the 2012 Social Security Trustees' Report, the program's Trust Fund is expected to run out of money in 2033, cutting benefits by about a quarter. Or in other words, that $1,234 monthly check is on track to become an inflation-adjusted $925.50, within the next 21 years.

That's Social Security's promiseIf you want to live your golden years on a less-than-minimum-wage lifestyle, go ahead and rely exclusively on Social Security. The program's trustees have been painfully clear about what you can really expect, both today and in the future once the Trust Fund empties. It isn't pretty. It isn't fun. But it's the future you will face if you're planning on Social Security as the sole source of your retirement income.

Fortunately, if there's a bright side to the problems Social Security is facing, it's that its Trust Fund's collapse is happening both fairly slowly and out in public. That combination means that you can see it coming and have about two decades to prepare for its arrival. Still -- that time doesn't give you clearance to ignore the problem. In the world of investing, 20 years is a decent amount of time to build a nest egg, but if you don't start now, the opportunity starts to evaporate quickly.

Use your time wellEven if all you're trying to do is cover the gap left behind when the Trust Fund evaporates, you'll still need a fairly large chunk of change. Using the 4% rule as a guide, you'll need around $92,550 -- nearly $100,000 -- to cover the typical expected Social Security shortfall. And remember -- that's just to get you back up to the minimum-wage lifestyle expected on average from today's Social Security.

If you'd like a lifestyle more in line with what you've been earning while working, you'll want to sock away more. Using that same 4% rule, for every $4,000 in annual income you want to replace, you'll need around $100,000 saved. The chart below shows the amount you'll have to put away each month for every $100,000 you want to sock away, based on different potential return rates and times:

Years to Go

10% Annual Return

8% Annual Return

6% Annual Return

4% Annual Return

20

$132

$170

$216

$273

18

$167

$208

$258

$317

16

$213

$258

$311

$373

14

$275

$325

$381

$445

12

$362

$416

$476

$542

10

$488

$547

$610

$679

8

$684

$747

$814

$886

6

$1,019

$1,087

$1,157

$1,231

Source: Author's calculations.

As you can see, it gets progressively tougher the longer you wait. And if you think that it is difficult to come up with $170 per month to invest now, imagine how much tougher it will be to come up with near $1,100 per month in 14 years. And all that's just to be able to cover $4,000 in annual income, some 20 years from now.

It's time to start investingIf you haven't been much of an investor before, getting started may well be the toughest part. But take heart -- even if you're worried that the results won't work out as you'd expect them to, know that even lousy investing still beats not investing at all. What's most important is to have a reasonable strategy and stick with it -- and let the time and the magic of compounding work to your advantage.

Your reasonable strategy may well be to buy an index fund, like the SPDRs (NYSE: SPY) that track the S&P 500. That would give you instant diversification and fairly broad market coverage, within the U.S. stock market. If going global is more your style, Vanguard's Total World Stock Index (NYSE: VT) ETF can help you cover the world, with one-stop investing. Of course, if going from "nothing" to "all stock" doesn't sit well with your psyche, adding broad bond exposure like Vanguard's Total Bond Market (NYSE: BND) ETF could help temper those concerns.

Any way you approach it, though, making a commitment to yourself to start consistently and regularly investing is a critical first step. With a mere 20 years or so left until Social Security's trust fund is expected to empty, the time to start taking action is now. Wait much longer, and all you'll be left with is the minimum-wage (or less) lifestyle that Social Security is offering its typical retiree.

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First, remember that saving and investing are not synonymous. 2. Better not invest unless you have saved at least 6 months of living expenses in an emergency fund. 3. Become debt-free. 4. Once steps 1-3 are in place, start investing, remembering that principal is always at risk

Once you are ready to invest, the rules of investing come into play, the first being do not invest money you cannot afford to lose. Most people cannot afford to lose their retirement savings. A major disconnect in our society is the mislabeling of retirement investments as retirement savings.

And since you will probably need about $2mil if you start today (because of the corrosive effects of inflation), and because no one knows the future so you should probably rely on the 4% assumption. Therefore, you will need to sock away $5460/month for 20 years based on the chart.

By the way, the depletion of the Trust Fund is not the catastrophe people make it out to be. The Trust Fund was designed in the 1980's to be depleted. In the 1980's FICA withholding went from 1% to about 7% to pay for the baby boomers.

If you put money in a Christmas account to buy Christmas presents, and then spend it on those Christmas presents, it is silly to complain about the depletion of the Christmas account. The Trust Fund is like the Christmas account.

As far as the Social Security Administration's benefit projections are concerned, if you look at your annual Social Security statement, you will see the trend is that The Trust Fund depletion is pushed further and further into the future and the possible shortfall less and less.

Here is another thing. The average person will see a 100% return of their Social Security "principal" in 2-5 years. Any future benefits are essentially return on "investment" (even though Social Security is not an investment instrument, but an insurance instrument).

Social Security was never intended to be a person's retirement fund, but a safety net preventing utter indigence in old age. Social Security is supposed to be a minimum and if the benefits are comparable to minimum wage, that sounds about right. As an insurance program, we were never meant to get back what we put in. Like any other insurance program, it is pooled risk. Those of us who are doing fine are helping take care of those who are not doing so well because the breadwinner died (survivor's benefits), or became disabled (disability benefits) or were never able to accumulate a history of high-paying jobs that would allow them to save for retirement.

That is why your FICA has a ceiling. Presumably if you are making more than $113,700 (2013 wage cap), you do not need the insurance and therefore you are not paying the premium on the amount of your wage exceeding $113,700.

Sending report...

Chuck Saletta has been a regular Fool contributor since 2004. His investing style has been inspired by Benjamin Graham's Value Investing strategy. Chuck also can be found on the "Inside Value" discussion boards as a Home Fool.